This section provides background information related to the present disclosure which is not necessarily prior art.
Precision cooling systems, such as those often used in cooling data centers, typically provide precision cooling both of temperature and relative humidity in the space being cooled. These cooling systems may utilize compressorized (air, water, glycol cooled) cooling units and/or chilled water cooling units. Such precision cooling systems often have the capability to operate based on temperature readings from several locations in the space being conditioned. These locations typically include, but are not limited to, the unit's inlet/return air, its discharge/supply air, or the inlets of racks/cabinets containing heat generating I.T. equipment (servers, storage, network switches, etc.). Customarily in precision cooling units, temperature and relative humidity are maintained as a pair for measurements, displays, and desired set points. When an operator of the cooling unit views a temperature from one of these locations, the operator expects that the relative humidity measurement will correspond to this location. Similarly, the desired temperature and relative humidity set points should correspond to this location (return, supply, or rack inlet).
One means of implementing the above measurement and display of temperatures and relative humidity is to place temperature and relative humidity sensors at each of the three (or more in the case of rack sensors) locations. This has a negative impact of increased cost for additional relative humidity sensors. An additional problem is that in some cases, the only practical location for the relative humidity sensor is the return air of the unit. This will rarely provide a correct unadjusted relative humidity reading relative to the other temperature sensor readings. The humidity at the supply (discharge) of the unit will vary significantly depending on the operating mode of the unit. This makes the unit supply a poor location for a relative humidity sensor. An alternative is to provide only one relative humidity sensor and have the user place the sensor at the correct location. This invites the problem of incorrect or less than optimal placement of the sensors.